Seabird colonies in Scotland have suffered one of the worst breeding seasons on record, experts have warned.

Reserves run by RSPB Scotland, the National Trust for Scotland (NTS) and the Scottish Wildlife Trust (SWT) have seen major failures of some species.

Breeding has been poor in guillemot, puffin, kittiwake and razorbill colonies, particularly in the west coast reserves.

Almost half of all seabirds in the EU nest around the coast of Scotland.

Previous breeding problems have been restricted to the east coast and the Northern Isles, with some birds forced to change their diet to less nutritious food after staples such as sandeels ran short.

We can only speculate as to why but climate change must be considered as a factor

Stuart HousdenRSPB Scotland

Figures for 2005 show just four guillemot chicks present at Ceann a' Mhara on Tiree from a total of 2,173 birds.

In a normal year, there would be 1,500 chicks on this Tiree seabird colony.

On St Kilda, owned and managed by the NTS, there was a spectacular breeding failure for puffins with only 26% of burrows producing chicks, which compares to a normal figure of 71%.

Canna's kittiwake colony of about 1,000 pairs saw its worst recorded year with barely five chicks fledged, and a dearth of guillemots and razorbills was also reported on the islands of Mingulay and Berneray.

International responsibility

Other west coast colonies such as the Treshnish Isles and Handa have also seen very poor breeding seasons.

On the east coast, there has been a slight improvement on last year's near total failure.

Stuart Housden, director of RSPB Scotland, said the figures were very disappointing.

He said: "We believe last year's breeding failures were due to lack of food for seabirds as a result of warming seas along the east coast which are a result of climate change.

Puffin numbers have also been hit badly

"This year the picture is more complex, with the problem spreading to the west. It is of great concern that some birds are having to find an alternative diet just to survive.

"This is the first time the west has been affected and we can only speculate as to why but climate change must be considered as a factor."

Richard Luxmoore, head of nature conservation at the NTS, said: "It is very worrying that places like St Kilda and Fair Isle appear to be suffering breeding failures in their seabird colonies.

"While it is normal for seabirds to suffer periodic failures, the frequency seems to have been increasing in recent years.

"Scotland has around 45% of all the seabirds in the European Union nesting on its coasts and we have an international responsibility to care for them."

The SWT has also reported a very poor breeding season on its reserves.

On Eigg, where kittiwakes would normally be expected to number 5,000, the highest number to be been seen this summer was 15.